Preliminary psychometric evaluation of the Multidimensional Psychological Flexibility Inventory in adults with spinal cord injury

Context/Objective: Psychological flexibility is a key treatment target in acceptance and commitment therapy and is increasingly relevant to rehabilitation research involving adults with spinal cord injury (SCI). This study examined preliminary psychometric properties of the Multidimensional Psychological Flexibility Inventory-Long Form (MPFI-LF) and Short Form (MPFI-SF) in adults with SCI.Design: Cross-sectional online survey with a two-week test–retest subsample.Setting: Community-based online recruitment across the United States.Participants: Adults with traumatic or non-traumatic SCI (N = 159; 50.3% female; mean age = 42.2 years). A subset of 59 participants completed the retest assessment.Outcome Measures: MPFI-LF, MPFI-SF, and other related measures to examine internal consistency, test–retest reliability, subscale intercorrelations, convergent validity, and floor and ceiling effects.Results: The MPFI-LF demonstrated good to excellent internal consistency across composite scores and subscales. The MPFI-SF showed acceptable to good internal consistency for most scores, although the Acceptance subscale showed poor internal consistency. Composite scores and most subscales showed moderate to good test–retest reliability, although several MPFI-SF inflexibility subscales showed poor to moderate stability. Subscale intercorrelations generally supported theoretically expected patterns, although experiential avoidance showed weak associations with other inflexibility subscales. Convergent validity was supported by moderate to strong correlations with related ACT process measures. No floor or ceiling effects were observed.Conclusion: Findings provide preliminary support for the MPFI, particularly the MPFI-LF, as a multidimensional measure of psychological flexibility and inflexibility in adults with SCI. Further research is needed to evaluate factorial validity, discriminant validity, and responsiveness.